Hypergolic fuel and method of propelling rockets



propellants and their utilization.

its entry into the combustion chamber.

lants in liquid form are advantageously utilized inasmuch HYPERGOLIC FUEL ANDMETHOD OF PROPELLING ROCKETS Cleveland R. Scott, Bartlesville, Oklar, and Arnold L.. Ayers, Idaho Falls, Idaho, assignors to Phillips Petrleum Company, a corporation of Delaware No Drawing. Application June 8,1953 Serial No. 360,356

8 Claims. c1. 60-354) This invention relates to rocket fuels. In one of its more specific aspects, this inventionrelates to hypergolic fuels.

In another of its more specific aspects, this invention relates to a method for propelling rockets.

Our invention is concerned with new and novel rocket A rocket or jet propulsion device, such as is discussed herein is defined as a rigid container for matter and energy, so arranged that a portion of the matter can absorb the energy in kinetic form and subsequently eject it in a specified direction.

The type rocket to which our invention is particularly ap- Rocket propelasthe liquid propellant material can be carried in a light weight, low pressure vessel and thereafter pumped into the combustion chamber. It is thus necessary, that the combustion chamber, although being strong enough to withstand high pressure and temperature, need be only large enough to insure combustion. Theflow of liquid propellant into the combustion chamber can be regulated at will so that the thrust resulting from continuous or intermittent bursts of power can be sustained. Intermittent burning of the fuel contributes to a longer life of the combustion chamber and of the thrust nozzle. Various methods and liquid combinations have been found useful as rocket propellants. Some propellants consist of a single material, and are termed monopropellants. Those propellants involving two materials are termed bi propellants and normally consist of an oxidizer and a fuel. Hydrogen peroxide and nitromethane are each well known monopropellants. Well known bipropellants include hydrogen peroxide or liquid oxygen as the oxidant with a fuel component such as ethyl alcohol-water, ammonia, hydrazine, or hydrogen; Additional known bipropellants include nitric acid as the oxidizer with aniline or furfuryl alcohol as the hypergolic fuel component.

When employing 90-100 percent nitric acid, i. e., white fuming nitric acid as the oxidizer in a rocket bipropellant, it is often necessary, dependent upon the specific fuel component, to obtain more effective ignition thanwould normally be obtained, by dissolving from 6'to 23 percent by weight of nitrogen dioxide in the white fuming acid, thereby forming red fuming nitric acid. A fuel component of the bipropellant-material of the type described herein, is spontaneously ignited upon contact- "taes Patent vide novel hypergolic fuels.

vention is to provide a method for producing immediate thrust to a'rocket type device. Another objectof the invention is to provide improved fast burning fuels. Other and further objects will be apparent to those skilled in the art uponstudy of the accompanying disclosure.

In accordance with the broad aspects of this invention, we have found that tert-butyl mercaptan is suitable for use in propulsion systems wherein hypergolic fuels can be utilized. We have found that tert-butyl mercaptan is hypergolic per se. The fuel constituent of the present invention, i. e., tert-butyl mercaptan, is also hypergolic in a diluted state when admixed with non-hypergolic mate rials, particularly hydrocarbons, even in a state of dilutionranging as high as 40 percent by volume of hydro-- carbon. Suitable non-hypergolic hydrocarbons which can also form a portion of the fuel composition include paraflins, cycloparaffins, olefins, cycloolefins, aromatics and the like inthe C C range or mixtures thereof,

preferably the normally liquid materials. Examples of such hydrocarbon fuels are n-hexane, n-heptane, benzene, kerosene, di-isobutylene, cyclohexane, isodecane, methylcyclohexane, gasoline, naphtha, diisopropyl, toluene, methylal, hexadecane, eicosane, hexacosane, pentatriacont'ane, picene, cyclononacosane, tetraphenylethylene, and the like. Hydrocarbons in the C -C range are preferred. I

In accordance with the present invention, an oxidizer and tert-butyl mercaptan are utilized in a volume ratio of approximately 110.7 to 1:15. Preferably at least about 1 volume of mercaptan is employed with each volume of fuming nitric acid or other oxidizer.

Other oxidizers or suitable oxidants for these hypergolic fuels, in addition to white or red fuming nitric acid, can be used in the bipropellant fuel compositions of our invention. Suitable oxidants include materials such as '1" hydrogen peroxide, ozone, nitrogen tetroxide, liquid oxygen, and mixed acids, especially anhydrous mixtures of nitric and sulfuric acids such as 8090 percent by volume white or red fuming nitric acid in 10-20 percent by volume anhydrous or fuming sulfuric acid.

It is within the scope of this invention to employ, preferably dissolved in the oxidizer, ignition catalysts or oxidation catalysts. These oxidation catalysts include certain metal salts, such as the chlorides and naphthenates of iron, zinc, cobalt and similar heavy materials. As an added feature of this invention, the mercaptan used in this invention is also useful for providing fast burning fuels suitable for use in rocket engines and the like wherein a hypergolic fuel is not necessarily required. For example, the fuel components of this invention are dispersed in a hydrocarbon, such as the hydrocarbon diluents described above. Even if the resulting solution is not hypergolic with an oxidant such as fuming nitric acid, it can be used, together with an oxidant and a suitable igniter, as

a rocket propellant. These fast burning fuels are particularly useful, if, for various reasons, a hypergolic fuel is i fuels.

ing the oxidizer. For this reason, such as bipropellant- The advantages of this invention are illustrated in the following examples The reactants and their proportions and their specific ingredients are presented as being typical and are not to be construed as being unduly limiting of the invention. Example I Tests were conducted wherein 0.13 ml. of tertiary Another object of the in-- WFNA, TBM Ignition Ram RFNA TBM, Ignition Ram,

1111. ml. Results m1. m1. Results LLM ml. TBM ml. TBM

0.4 0.13 3.1 0.4 0.13 3.1 0.3 0.13 2.3 0.3" 13 2.3 0. 2' .13 1. s 0. 2 0.13 1. 0.15 s 0.13 1.2 0.15 -=0.13 1.2 0. 1 0. 13 0.8 0. l 0. 13 0.8

These tests demonstrate thatapproxim-ately equal vol-- umes of acid and fuel are required before spontaneous ig- .nitions will occur consistently. Fuel rich mixtures of 3 of tertiary butyl mercaptan were dropped intoa 1" x8 test tube containing 0.3 ml. of fuming nitric-acid. Re

sults of these tests are recordedin the followingtable:

These results demonstrate 'that tertiary 'butyl mercaptan retains its self-ignition properties when fuming nitric I acids are used as oxidants in dilutions ranging as high as 40 volume percent of hydrocarbon diluen't.

As Will be evident to those skilled in the art, various modifications "of this invent-ion: can be :made zorfollowed in the light of this disclosure .without :departing ;froms the spirit and the scope of this invention. i,

We claim: y 1 r 1. A fuel which is -hypergolic =with an oxidizer com- 1 prising at least -60 .percent by volume of tert-butyl amen captan and up to 40 percentby' volume of a-nonmally -WFNA, TBM, Ignition Ram, RF-NA, TBM, Ignition: Ram,

ml. ml. Results E l-JIM m1. m1. Results w ml. TBM ml. TBM

0.3 0.1 NI 3.0 0.3 0-1 3 NI s 3.0 0. 3 0. 2 Ignition 1. 5 0.3 0. 2 Ignition 1.3 0.3 0.25 do 1.2 0.3 0.25 do 1.2 0.3 0.3 I 1.0 0.3 0.3 1.0 0.3 0.35 0.9 0.3 0.4 0.8

I 0.3 .0. 4 0. s 0.3 0. 0 0. s

1 2 ignitions out of 4 tests. Y 7

These tests also demonstrate that approximately equal volumes of acid and fuel are required before spontaneous ignitions will occur consistently.

Example [I 0 Percent Vol. of Actual WFNA, ml. Dilution TBM+nvol. Ignition we n-heptane hcptane, TBM, Results ml. TBM

ml. ml.

10 0. 2 0. 18 NI 1. 7 10 0. 0. 2-25 IgnitioIn. 1. 3 10 0.3 0.27 0 -l.1 20 0.25 0.2 ..NI -1.5 20 0. 3 0. 24 Ignition. 1. 3 20 0.35 0. 28 .do 1. 1 30 0.35 i 1. 2 30' 0.4 11.1 30 0. 45 1'. 0 40 0. 62 0. 8 40 0. 75 0. 7 40 1. 0 0. 5

Percent V01. of Actual RFNA, ml. Dilution TBM+nvol. Ignition 1111- n-heptane heptanc, TBM Results m1. TBM

rnl. ml.

0. 10 0.2 0. l8 NI 1. 7 10 0. 25 0. 225 Ignition" 1. 3 .10 0. 3 1. 1 20 0. 25 1. 5 20 0. 3 1. 3 20 0. 1. 1 30 0. 35. .1. 2 '30 0.4 1. 1 30 0.45 1. 0 40 0. 62 N 0. 8 40 0. 75 0. Ignition.- i 0. 7 .40. 1.0. 0. 0 0.5

v captan and up to 40 percent by volume of a normally:

"in such proportions as to produce spontaneous ignition 'mercaptan being not more than 120.7.

liquid hydrocarbon in the C to C range. V 2. A fuel which is hypergolic with .an oxidizer-corn, prising at least 60 .percent by volume of tert-butyl mer liquid hydrocarbon in the C to C range. ,7

.3. A fuel comprising normally liquid hydrocarbons the C to C range and from 1 to 20 percentby volume of itert-butyl mercaptan. y

4. A fuel comprising normally liquid hydrocarbons, n, the C to C range and from 5 to 20 percent by volume of tert-butyl mercaptan. r

5. A method for applying immediate thrust to a mass, comprising introducing separate streams-of an oxidan' and fuel. component of a bipropellant into-contact wit each other in a combustion chamber'o f a reaction motor in such proportions as to produce spontaneous ignition',.; said fuel component consisting essentially of tort-but 1" mercaptan and the ratio of said oxidizer of tertebsutyli 6. A method for applying immediate thrust to a comprising introducing separate streams of an'oxidan and fuel component of a bipropellant into contact w each other in a combustion chamber of a reaction mo to said-fuel component consisting essentially of tertibptyl; mercaptan and the ratio of said oxidizer to tert-butyl mercaptan being in the range of 110.7 to 1:15. 3 s 7. Amethod for applying immediate thrust to amasscomprising introducing separate streams of an oxidant. and fuel components of a bipropellant into contact w' each other in a combustion chamber of a reaction moto in such proportions as toproduce spontaneous ignition,

of white fuming nitric acid, red fuming nitric'acid,-;hy drogen peroxide, ozone, nitrogen tetroxide,-liquid oxygen,. and a mixture-of atleast percent by volume fu ning nitric acid and up to 20 percent -by volume furning sul-l furic acid,.and a ratio of said oxidizer to tert-butyl mercaptan beingin the range of 1:0;7 to 1:15. V 1

8. A method for applying immediate thrust to a masscomprising introducing separate streams of an oxidant and fuel components of a bipropellant into contact with each other in a combustion chamber of a reaction motor in such proportions as to produce spontaneous ignition, said fuel components comprising at least 60 percent by volume of tert-butyl mercaptan and up to 40 percent by volume of normally liquid hydrocarbons, said oxidant being selected from the group consisting of white fuming nitric acid, red fuming nitric acid, hydrogen peroxide,

ozone, nitrogen tetroxide, liquid oxygen, and a mixture 10 References Cited in the file of this patent UNITED STATES PATENTS Sayward et a1. Nov. 22, 1949 Viles sa a June 12, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,859,587 November 11, 1958 Cleveland R. Scott et a1.

certified that error appears in patent requiring correction rested below.

second. occurrence,

the -printed specification It is hereby and that the said Letters of the above numbered Patent should read as cor 601mm 4, line 52, for "of",

"and sealed this 22nd day 0 1 September 1959'.

(SEAL) Attest: v KARL H. YAXLINE ROBERT C. WATSON Commissioner of Patents Attesting Officer 

5. A METHOD FOR APPLYING IMMEDIATE THRUST TO A MASS COMPRISING INTRODUCING SEPARATE STREAMS OF AN OXIDANT AND FUEL COMPONENT OF A BIPROPELLANT INTO CONTACT WITH EACH OTHER IN A COMBUSTION CHAMBER OF A REACTION MOTOR IN SUCH PROPORTIONS AS TO PRODUCE SPONTANEOUS IGNITION, SAID FUEL COMPONENT CONSISTING ESSENTIALLY OF TERT-BUTYL MERCAPTAN AND THE RATIO OF SAID OXIDER OF TERT-BUTYL MERCAPTAN BEING NOT MORE THAN 1:0.7. 